-6.72% is the change from 685 to 639
Calculation steps:
[( 639 - 685 ) ÷ 685] x 100 = -6.72%
Formula
Percentage change = [(639 - 685) / 685] x 100
Subtract the new number by the original number
639 - 685 = -46
-46 ÷ 685 = -0.06715328467153285
-0.06715328467153285 x 100 = -6.72%